This project as well as project number ZO1-CP-04842-06-LVC, studies the biochemical and biophysical properties of nucleic acids of mammalian oncornaviruses. A summary of our major findings for this fiscal year are as follows: 1. Poly(C)-rich and poly(G)-regions were detected in avian, feline, murine and primate leukemia and/or sarcoma viruses. 2. Gazdar murine sarcoma virus (Gz-MSV) is closely related to Moloney murine sarcoma virus (M-MSV) and Gz-MSV is possibly a variant of M-MSV. 3. The MSV-specific region in both Gz-MSV shared homology with hamster leukemia virus from F-2833 cells as determined by hybridization studies. BIBLIOGRAPHIC REFERENCE: Phillips, L.A. and Pang, R.H.L.: The detection and characterization of polynucleotide sequences in the RNA of mammalian oncornaviruses. In Clemmesen, J. (Ed.): Bibliotheca Haematologica, No. 43. Basel, Switzerland, S. Karger AG, 1976. pp. 460-464.